how to get created at in join query in laravel code example

Example 1: join in laravel eloquent

$customer = DB::table('customers')
                ->join('shops', 'customers.shop_id', '=', 'shops.shop_id')
                ->where('customer_contact', $contact_no)
                ->get();

Example 2: join in laravel

$subCategories = Subcategory::join('categories', 'subcategories.category_id', '=', 'categories.id')
                              ->select('subcategories.*', 'categories.name AS cname')
                              ->orderBy('id', 'desc')
                              ->get();